Yes, Bloodlines is about a bunch of different monsters mobs — e.g. the werewolf mafia, the shapeshifter mafia, etc. — ruling Chicago, and a young cop-in-training whose fiancée gets killed in the middle of the monster war. This obviously turns him into a cross between Van Helsing and Eliot Ness, courtesy of a little help from the Winchester brothers. Here's the first trailer:

It sounds to me like a World of Darkness sourcebook that got way out of hand, but you can judge for yourself on April 29th, when the backdoor pilot airs as part of Supernatural's ninth season, as Sam and Dean stop by Chicago to... fight mobster monsters. Monster mobsters? Monbsters? Never mind.